The cover. The front has the eponymous monster breaking out of a TV set while seemingly glaring menacingly at the viewer, and the back features a closeup of the monster's face.
The movie's ending, which is surprisingly creepy for a lighthearted movie. Snyder talks to a monster statue, then the monsters eyes suddenly start glowing red and shows Snyder...something. Whatever Snyder saw, he feels a sense of twisted enlightment and the movie ends on a freeze frame of him laughing maniacally. It's implied that he transformed into Beastur, the franchise's Big Bad.
Special Effect Failure: To the point that the toy itself (which is used on the cover) looks more convincing than the costume.
Ugly Cute: Monster's friendly and childlike nature, as well as his high-pitched Speech-Impaired Animal-styled voice give him an unusually endearing charm.